refactor: split glm.c into colibri.c + 4 header modules

Rename glm.c → colibri.c and extract four self-contained modules
into header-only files (same pattern as st.h/tier.h/grammar.h):

  quant.h      (672 lines) — SIMD matmul kernels, quantization
  sample.h     (143 lines) — RNG, top-p sampling, stop-set
  kv_persist.h (121 lines) — .coli_kv disk persistence
  telemetry.h  (189 lines) — dashboard protocol, stats, usage

Main engine file shrinks from 6588 to 5396 lines (−18%).

Build system: primary target is now colibri$(EXE); `make glm`
remains as a phony alias for backward compat. CI, setup.sh,
coli CLI, and all 10 test files that include the engine are
updated. make check passes (C + Python, 73 tests, zero warnings).

.github/workflows/ci.yml

@@ -12,8 +12,8 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - name: Build glm
-        run: cd c && make glm
+      - name: Build colibri
+        run: cd c && make colibri
       - name: C test suite
         run: cd c && make test-c
 
@@ -105,11 +105,11 @@ jobs:
           make cuda-dll CUDA_ARCH=sm_80
           test -f coli_cuda.dll || { echo "cuda-dll reported success but produced no DLL" >&2; exit 1; }
           echo "coli_cuda.dll built (MSVC host)"
-      - name: make glm CUDA_DLL=1 (host links backend_loader, not cudart)
+      - name: make colibri CUDA_DLL=1 (host links backend_loader, not cudart)
         shell: msys2 {0}
         run: |
           cd c
-          make glm CUDA_DLL=1
+          make colibri CUDA_DLL=1
           test -f glm.exe || { echo "glm CUDA_DLL=1 reported success but produced no exe" >&2; exit 1; }
           echo "glm.exe built against the DLL loader"